Before anyone knew the name Juan Lagares, the Mets were gaga over Matt den Dekker’s defensive potential.

Then den Dekker broke his wrist in spring training last year, creating an opening for Lagares, who has hardly looked back since. But den Dekker is still a special defensive player — a point he demonstrated Monday in his first start this season for the Mets.First, den Dekker reached over the center-field fence to steal a home run from Ryan Howard. Later, he easily threw out Reid Brignac attempting to score from second.

“I know it’s tough, there’s a lot of guys who want to be out there and playing,” den Dekker said after the Mets thrashed the Phillies 11-2 for their sixth victory in seven games. “I just try to stay ready and get out there and play like I can.”

Den Dekker had been optioned to Triple-A Las Vegas on Sunday but was told to remain in town until the Mets were sure about Lagares’ status. Lagares was scratched from Saturday’s starting lineup with rib cage soreness and ultimately placed on the disabled list Monday.Collins had told den Dekker late last week he would be in Monday’s starting lineup. All bets seemed off with den Dekker’s demotion that brought the Mets a needed bullpen arm in Dana Eveland, but Collins was rewarded for sticking to his original plan to keep den Dekker around and giving him the start.

It’s understandable if the Mets (28-29) had to be threatened with arrest if they didn’t leave the premises. Though three of the games here went extra innings, the Mets won four of five in the series and made it clear the Phillies are the worst team in the NL East.Den Dekker’s night included a single as part of the Mets’ four-run sixth that gave Bartolo Colon space. The Mets turned the game into a runaway with six runs in the ninth, highlighted by Wilmer Flores’ first career grand slam.